Sjöström Audio DIY forum

Projects => Headphone amplifiers => Topic started by: krainov on May 01, 2018, 12:58:25 PM

Title: QRV-03 question
Post by: krainov on May 01, 2018, 12:58:25 PM
Hi, P-A!
Before building QRV-03 I would like to ask you a question about the way the EMI filter may be inserted before the power in.
I'm from Russia, and our power lines are too noisy, so it is obvious - ones must have the EMI filter on such a sensitive equipment.
Here is the schematics for the EMI filter topology that I use for a long time in different units and it works well.
https://yadi.sk/i/DJ3mKwR33V5wFo (https://yadi.sk/i/DJ3mKwR33V5wFo)
So the question is:
The filter must be connected to chassis of the unit. And the 0V of the QRV-03 is also. Will this connection of filter will effect the QRV-03 with filtered EMI noise?

Thanks!
Title: Re: QRV-03 question
Post by: peranders on May 01, 2018, 01:25:46 PM
The normal reason to have a filter as you have shown is that the power supply is emitting noise so the filter is blocking noise going OUT on the mains. This is very common of you have a switch mode power supply. I would recommend that you start without filter and see how it goes.
Title: Re: QRV-03 question
Post by: krainov on May 01, 2018, 01:35:52 PM
Thanks!
And what about the optional parts in the schematics of QRV-03 (they are marked with comment: Values not determined yet.)? Do I have to omit them?
Title: Re: QRV-03 question
Post by: peranders on May 01, 2018, 01:41:59 PM
You can omit them.
Title: Re: QRV-03 question
Post by: krainov on May 01, 2018, 02:56:18 PM
Thanks!
Title: Re: QRV-03 question
Post by: krainov on May 03, 2018, 06:34:27 PM
heaveno P-A!
The Input stage channel and Current amp and output stage connected only with one port? It is not clear for me coz the port names are differ.
Are they connected only here? (See the attachment)
Title: Re: QRV-03 question
Post by: peranders on May 03, 2018, 07:10:33 PM
Net names with EXACTLY the same name are connected together.
Title: Re: QRV-03 question
Post by: peranders on May 03, 2018, 07:18:06 PM
You can also take a look at the application note AN-211. I have also a file with a high resolution than the one you can find on the net. Send me an email in case you want it.

http://www.analog.com/media/en/technical-documentation/application-notes/58052492001115525484056221917334AN211.pdf
Title: Re: QRV-03 question
Post by: krainov on May 05, 2018, 11:35:17 AM
Yes, please! Send it to krainovrv(at)yandex.ru
Title: Re: QRV-03 question
Post by: peranders on May 05, 2018, 01:27:58 PM
Sent :) If you want the patent document, I have it. let me know if you want it.